Electrolytic method and apparatus



1931' R, A. WILKINS 1,820,204

ELECTROLYTIC METHOD AND APPARATUS Filed Jan. 12, 1929 Invefl/Z'o 2' Richard 12. W232i: wins,

I .Patented .Aug. 25; 1 931 UNITED STATES lPATE NT, OFFICE -BIGHABD A. WILKINB, OI IBEVIQLY, IASBA G'E'IIl'SE'IMIS, ABSIGNOB TO INDUSTRIAL DEVELOPMENT CORPORATION, OI SABER, KASBAOHUBETTB, A CORPORATION 01' MAINE nmcmnnre mn'rnon nnn"urmrus Application filed January 12, 1929. Serial No. 382,108.

My invention pertains'to improvements in electrolytic products, methods and apparatus, and particularly but not exclusively to metal foil and methods and a paratus for producing the same by electroeposition.

The invention in some of its aspects is an improvement on that disclosed in United States patent to Merritt 1,601,690, Se tember 28, 1926, and will be best understood rom the i following description when read in the light of the accompanying drawings of one specific embodiment of apparatus for use in practising theinvention, while the scope of the invention will be more particularly pointed out in the appended claims.v

In the drawings r Figure 1 is a more or less schematic arrangement of apparatus constructed according to the invention, parts being shown in section;

Fig. '2 is a section on the line 2-2 of Fig. 1; and

Fig. 3 illustrates a detail.

Referring to the drawings, I have shown a drum 1 carried by a shaft 3, the latter mounted in bearings 5 so that the drum may be rotated. As illustrated, the drum comprises a sleeve 7 of copper or other material providing a conductive surface,'which sleeve at opposite ends thereof is carried by members 9 non-rotatably mounted on the shaft, these members preferably formed to provide frusto-conical end surfaces 11 for the drum and being of non-conductive material such as wood, porcelain, or the like. As shown, the drum is provided with rings 13 of rubber, or other non-conductive material, which closely abut with the ends of the sleeve 7 so that the metal sheet 15 which is deposited on the sleeve, as will hereinafter be described, will be formed with uniform unbroken edges.

Herein, the surface of thesleeve 7 constitntes a cathode on which the sheet 15 of material to be formed is deposited from the electrolyte. For facilitating stripping the sheet from the surface of the cathode, the latter preferably is.coa'ted with amalgam, which amalgam may be composed of such proportions of mercury and tin asto form a rather soft masspermitting the surface of may constitute an insoluble anode cooperating with the cathode surface. As shown, the shaft 3 is provided with an insulating coupling, schematically indicated at 22, which coupling isolates the portion of the shaft adjacent. the cathode from the remaining portions thereof. A source of low potential,

direct current, electromotive force of high current capacity, schematically indicated by the battery 23, has its positive terminal connected to the insoluble anode 21 by a conductor 24 and its negative terminal connected to the cathode by a conductor 25 in electrical communication with a brush27, the latter cooperating with a ring 29 of'conductive material mounted on the shaft 3, while the shaft is placed in electrical communication with the sleeve 7 by a conductor 31. y

In the present embodiment of the invention, mechanism is provided for reciprocating the cathodesurface in opposite directions by giving the shaft 3 an oscillatory movement, this oscillatory movement being relatively rapid and moving the drum through a greater angle in one direction than the other, so that there is effected a relatively rapid motion between the electrolyte and cathode with a. resultant motion which rothe clutch 41 is in engaged condition and in the dpposite direction when the clutch 45 is in engaged condition, and that by alternately causing engagement of the two clutches, and keeping one clutch in engagement for a longer period than the. other, the shaft Wlll. be oscillated with movement through a greater angle inone direction than 1n the other.

As illustrated, the electro-magnetic clutches 41. and 45 have energizing windings schematically indicated by the inductance coils 47 and 49. As shown in Fig. 1, the left hand terminals of the coils 47 and 49 are m electrical communication with the left hand terminal of a source of electromotive force indicated by the battery 51, while the opposite terminals of these coils, respectively, are in electrical communication with the brushes 53 and 55, cooperating with a distributor 57. As schematically indicated in Fig. 1, the distributor comprises a disk 59 of non-conductive material carrying a contact system comprising the three radially disposed arms 61, the latter being placed in electrical communication with the right hand terminal of the source of electromotive force 51 by means of a, conductor 63 connected to a brush 65 in contact with the distributor hub 67 from which radiate the distributor contacts. 61. Conveniently the distributor may be rotated by an electric motor schematically indicated at 69.

It will be observed, that as the distributor 57 is rotated, the brushes 53 and 55 w1ll alternately contact with the radial arms 61 of the distributor, so as alternately to energize the electro-magnetic clutches 41 and 45. By positioning the brushes 53 and 55 at different radial distances from the axis of rotation of the distributor, one clutch will be energized for a longer time than the other. Gonvenicntly the brushes 53 and 55 may be mounted in brush holders 71 (Fig. 3) adiustably mounted for sliding movement longitudinally of a support 73, so that the radial distances of the brushes 53 and 55 from the axis of the distributor may be varied, and thus the amplitude in each direction of the oscillatory or reciprocatory movement of the cathode surface. As shown, the motor 69 which drives the distributor is indicated as of the shunt wound type with a rheostat in the field winding. so as to enable the speed of the motor to be varied, by which means for a given setting of the brushes 53 and 55 the amplitude of oscillation of the cathode may be varied.

Herein, for stripping the sheet 15 from the cathode surface, provided by the cylinder 7, I have provided a reel 75 mounted on a shaft 77, which shaft is geared to the shaft 3 by the pulleys 79 mounted on the respective shafts and connected by the belt 81. As

but by this prior ed on arms 83 pivoted at 85 to a vertical support 87.

W th the a paratus illustrated, the electrolyte is cause to flow in a continuous stream,

preferably swiftly, through the trou h 19, the 7 electrol e being circulated throug a mass 89 of e ectrolyte replenishing material contamed in a tank 91. As shown, the electrolyte leaving the tank 91 passes through a conduit 93 and hence down an incline 95 to the trough 19, the head between the tank and trough giving the electrolyte considerable velocity as it passes through the latter. The surface of the liquid in the trough preferably is maintained approximately horizontal, or parallel to the longitudinal axis of the drum 1, by use of an 'underflow gate 97 and wier 99, both of which conveniently may be mounted for adjustable movement in a vertical direction. The electrolyte passing from the trough 19, as shown falls into a tail-stock 101, whence it is pumped through a pipe 103 to discharge through an outlet 105 into the tank 91, a bypass connection 107 being provided'for bypassing any desired portion of the electrolyte around the tank, the outlet 105 and by-pass connection 107 respectively rovided with the valves 109 and 111 for enab ing this result to be secured.

The invention is applicable to forming sheets of metals which may be electro-deposited from aqueous solutions of their salts. I have found the invention particularly adapted for making copper foil, say material in the order of 0.0002 inches in thickness, al-

though, dependent somewhat upon economic considerations, much thicker material, say material having a thickness in the order of 0.01 inches, may be made b it. Heretofore copper foil has been made y a mill process comprising alternate rolling and annealing, Cprocess it i? impossible economically to pro uce copper oil less than about 0.001 inches in thickness.

The copper-foil produced by the present invention I have found is superior in many aspects to foil produced by the usual rolling strength is uniform in all directions from points on its surface, the rolled material, as will be understood by those skilled in the art, being of high tensile strength in the direction of the grain and of very much reduced tensile strength in directions transverse to the grain. Although the material made according to the present process may, in some instances, have a slightly lower tensile stren thv than that in the direction of the grain of oil produced by prior processes, it has a much processes, particularly in that its tensile w shown, the reel 75 will oscillate with the drum higher tensile strength than the mean tensile 1...

strength of the latter. Copper foil produced by the present invention is distinguished in one aspect from electro-de osited metals heretofore produced in that it has the high degree of malleability .and ductilitycommon- 'ly associated with forged and rolled metals gallonsper minute, where the angular oscil latory movements of the cathode surface in opposite directions vary from degrees in one direction and 60 degrees in the other direction to from 35 degrees in one direction and 30 degrees in the opposite direction. with twenty oscillations per minute, the latter resulting in one revolution of the cathode in 3.6 minutes. The electrolyte replenishing materialcemployed in this example consists of about thirt pounds of #10 mesh jigconcentrate La e copper, placed in the tank for electrolyte replenishing material, the by-pass valves for controlling the metal content of the electrolyte being regulated to maintain the copper sulphate (CuSQ .5I-I O) concentration between 20 and 36 ounces per gallon of solution, and the sulphuric acid concentration between 16 and 8 ounces of commercial 66 degrees Baum acid per gallon of solution.

I have found that the thickness of the foil may be regulatedby varying either the resultant speed of revolution of the cathode surface, or, with a given number of oscillations per minute, by varying the difference in amplitude in opposite directions of the oscillations. For example, at twenty oscillations per minute, and at a current density of about 200 amperes per square foot, a 5 degrees difference in amplitude will produce, in the above example of the practice of the invention, foil of about 0.0003 inches in thickness, and, a 2% degrees difference, foil of about 0.0006 inches in thickness. osition also is affected by the current density, and I have found that by passmg the electrolyte past the cathode in a swiftly flowing stream, while reciprocating the cathode" transversely relative to the stream, high current densities, say for example from 200 to 300 amperes per square foot, may be employed without burning the metal deposited.

Under some conditions of use of the product, say when the foil is used for making electrical condensers, it maybe of advantage to have it minutely perforated, which I have The rate of depfound convenientl may be effected by maintaining'a relative high hydrogen ion concentration of the elbctrolyte, say by using an electrolyte having a sulphuric acid concen-. tration of 30 ounces, 66 degrees Baum, .per gallon of electrolyte in the above example of the practice of the invention.

For some conditions of use of the product, it is desirable to have the foil coatedwith soldering material, and conveniently for this.

purpose I electrolytically deposit soldering material on the sheets of foil, after they are produced as above described. With copper foil conveniently this may be done by first depositing on the sheets a layer of electrolytic tin,'say by cleaning the sheets and then guiding them through an electrolytic cell containing a stannous chloride electrolyte, the sheets being made the cathode of such cell. After the tin deposit is formed, the sheets may be washed and a coating of lead deposited thereon in a similar manner, using lead fluorosilicate as an electrolyte. If desired, a

second layer ofc'tin may be applied for dproducing a surface less susceptible to oxi zation than a lead surface. These alternate layers of tin and lead, which may be applied to both sides of the copper foil, will form a soldering alloy when heat is applied to the foil, enabling the foil readily to be soldered. When the material is to be used for fabricating electrical condensers, or in other situations where it is undersirable to employ a flux soldering, the layers of tin and lead may consist of no more than a blush of these materials, say as will beproduced by causing each portion of the sheets to remain in the stannous chloride baths about 5 seconds and in the lead fluorosilicate bath about 10 seconds, in which case sheets placed in contact layers may be increased, say by allowing the sheets to remain in the baths four or five times as long, in which case sheets placed in contact may be soldered by applying heat, say by application of a hot iron, to the points to be soldered, with or without the use of flux, as found most expedient.

ject,'matter of my co-pending applications Serial No. 359,773, filed May 2,, 1929, and

Serial No. 472,684, filed August 2, 1930, while the electric condenser mentioned herein forms the subject matter of my co-pending applicaq tion Serial No. 364,169.,filed May 18, 1929.

It will be understood that my invention is not limited to the specific embodiments of apparatus, method, and product above de- The foil herein described forms the sub-.

as I

scribed, but that within the scope of the invention wide deviations'may be made from these without departing from the spirit of the invention. y

Claims: 1'. Electrolytic a paratus com rising, in combination, an e ectrolytic cel having a cathode, means for guiding the electrolyte in 5 a swift-flowing continuous stream along the cathode surface in contact therewith, and means for reciprocating said cathode for reciprocating said surface thereof transversely to the direction of flow of said stream while depositing thereon.

'2. Electrolytic apparatus comprising, in combination, an electrolytic cell having a cathode, means constituting an anode for guiding the electrolyte in a swift-flowing is continuous stream along the cathode surface,

in contact therewith, and means for reciprocating said cathode for reciprocating said surface thereof transversely to the direction of flow of said stream.

3. Electrolytic apparatus comprising, in combination, an electrolytic cell having a cathode, means constituting an insoluble anode having a surface in relativel close proximity to said cathode for guiding the elec- 26 trolyte in a swift-flowing continuous stream along the cathode surface in contact therewith, and means for reciprocating said cathode for reciprocating said surface thereof parallel to said surface of said anode and transversely to the direction of flow of said stream.

4. Electrolytic apparatus having, in combination, an electrolytic cell, means providing a cathode with an endless cathode surface, means constituting an anode having a surface in relatively close proximity to said cathode surface, means for passing the electrolyte from one side of said cathode surface to the other in contact therewith in a swift-flowing continuous stream,-and means for moving sa1d cathode to reciprocate said surface thereof in direct-ions transverse to said stream and parallel to said surfaceof said anode while progressively advancing said cathode surface in one direction of such reciprocation.

5. Electrolytic apparatus having, in combination, an electrolytic cell, means providing a cathode with an endless cathode surface, means constituting an insoluble anode having a surface in relatively close proximity to said cathode surface for guiding the electrolyte from one side of the latter to the other in contact therewith in a swift-flowing continuous stream, and means for moving said cathode to reciprocate said cathode surface in directions transverse to said stream and parallel to said surface of said anode while progressively advancing said cathode surface in one direction of such reciprocation.

6. Electrolytic apparatus having, in combination, means providing a movable endless cathode surface, means constituting an insoluble anode having a surface in relatively close proximity to said cathode surface for V guiding the electrolyte in a swift-flowing continuous stream past the latter from one side thereof to the other, means for moving saidcathode for reciprocating said cathode surface in directions transverse to the direct1on of flow of said stream and parallel to said surface of said anode while progressively advancing said cathode surface in one of said directions 'of reciprocation, and means for stripping from said surface an endlesssheet 0 material deposited thereon from the electrolyte. f

7. Electrolytic apparatus having, in combination, means providing a rotatable cylindrical cathode, means constituting an insoluble anode having a surface in proximity to the surface of said cathode for guiding the electrol to in a swift-flowing continuous stream ongitudinally past a portion of said surface of said cathode in contact therewith, means for oscillating said cathode about its longitudinal axis, the de tee of oscillatory movement in one direction being greater than that in the op site direction, and means for stripping rom said surface an endless sheet of material deposited thereon from said electrolyte.

8. Electrolytic apparatus having, in combination, means providing a rotatable c lindrical cathode, means providing an inso uble anode constituting a trough the walls of which are in close proximity to the surface of said cathode, means for passing an electrolyte through said trough axially of said cathode in a swift-flowing continuous stream, means for re idly oscillating said cathode about its longitudinal axis, the degree of oscillation in one direction being slightly greater thanthat in the opposite direction, and means for stripping fromsaid cathode an endless sheet of foil deposited thereon from said electrolyte.

9. The method of producing metal foil which consists in rapidly reciprocating a cathode invclose proximity to an insoluble anode, and passing a metal bearing electrolyte in a swift-flowing continuous stream between said cathode and anode in contact therewith.

10. The method of producing copper foil which comprises depositing copper on a rapidly reciprocating cathode from. a swiftfiowing continuous stream of copper bearing electrolyte. V

'11. The method of producing copper foil which consists in rapidly reciprocating a cathode in close proximity to an insoluble anode, and passing a copper bearing electrolyte in a swift-flowing continuous stream between said cathode and anode in contact therewith.

12. The method of producing copper foil which comprises depositing copper on a rapidl oscillating cylindrical cathode from a swift-flowing stream of copper bearing electroiyte, which latter is guided axially of said cathode in contact therewith by means constituting an insoluble anode in close proximity to the cathode surface.

In testimony whereof, I have signed my name to this specification.

RICHARD A. WILKINS. 

